Accompanied by development of Internet of Things (IOT), there may be increasing opportunities of designing an antenna. For this reason, an antenna designing device is demanded that enables designing even by a designer not having sufficient knowledge about antennas. An antenna designing device is known that reads out a model from a model memory unit based on an instruction from a designer, lets the designer make an input for changing the shape of the model using information of the length, and calculates a matching condition, a communication distance, and the like of an antenna for display (see Patent Literature 1, for example). With such an antenna designing device, a designer may acquire a matching condition, a communication distance, and the like of an antenna only by inputting information of the length of a part that is desired to be changed, whereby even a designer not having sufficient knowledge about antennas may efficiently design an antenna.